* [Server][Spring] support interface and implementation classes for API controllers
* Omitted new string calls
* Added Log messages
* remove else
* Removed redundant if
* Update missed ;
* add nullable case to spring test spec
* generate samples for changed spring input
* add nullable case to general test spec
* generate samples for changed general input
* generate samples again
* generates samples again
* re-build from new sources, generates samples again
